Tetrahydrofuran polycarboxylic acids

ABSTRACT

WHEREIN R1, R2, R3, R4 and R5 are hydrogen or carboxylic acid groups, at least one of R1, R2, R3 and R4 being a carboxylic acid group when R5 is a carboxylic acid group are useful as complexing agents and/or detergency builders. The ester forms of such compounds, as well as the acids are useful as intermediates for production of the salts.   Salts of tetrahydrofuran polycarboxylic acids represented by the formula

United States Patent [191 Rapko 11] 3,835,163 Sept. 10, 1974TETRAHYDROFURAN POLYCARBOXYLIC ACIDS [75] Inventor: John N. Rapko, St.Louis, Mo.

[73] Assignee: Monsanto Company, St. Louis, Mo.

Linn et al., J. Amer. Chem. Soc. Vol. 87, 1965, pp. 3657-3665. Linn etal., J. Amer. Chem. Soc. Vol. 85, 1963 pp. 2032-2033.

Primary Examiner-Henry R. Jiles Assistant Examiner-Mildred A. CrowderAttorney, Agent, or Firm-Thomas N. Wallin; J. E. Maurer; Neal E. Willis[5 7] ABSTRACT Salts of tetrahydrofuran polycarboxylic acids representedby the formula wherein R R R R and R are hydrogen or carboxylic acidgroups, at least one of R R R and R being a carboxylic acid group when Ris a carboxylic acid group are useful as complexing agents and/ordetergency builders. The ester forms of such compounds, as well as theacids are useful as intermediates for production of the salts.

11 Claims, N0 Drawings BACKGROUND OF THE INVENTION This inventionrelates to novel tetrahydrofuran polycarhoxylic acids and salts usefulas complexing agents and detergency builders; to detergent formulationscontaining such compounds and to ester forms of such compounds useful,inter alia, as intermediates for preparation of the salts and acids.

The utility of compounds characterized by the ability to complex variousmetal and alkaline earth metal ions (particularly ions such as calciumions which contribute to hardness of water) in aqueous media and/orprovide, in combination with various detergent surfactants, detergentformulations of enhanced cleansing ability is well recognized by thoseskilled in the art. Such compounds are used in water treatingapplications (e.g. to soften water)and/or as detergency builders.

Although many compounds having complexing and- I /or detergency builderfunctionality are known the provision of novel compounds composed ofonly carbon, hydrogen and oxygen and having such functionality isdesirable.

Since most known complexing agents form complexes with water hardnessions on a 1:1 mole basis, novel compounds having the ability to complexgreater quantities of such ions are particularly desired.

SUMMARY OF THE INVENTION It is an object of this invention to providenovel compounds useful as complexing agents and/or detergency buildersand intermediates for the synthesis of such compounds. A further objectof the invention is to provide novel detergent formulations containingthe builder compounds of this invention.

The compounds of this invention are tetrahydrofuran polycarboxylicacids, their salts and esters whose structure, synthesis, and use willbe understood from the following description of the preferredembodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The compounds of the presentinvention are represented by the formula wherein X is hydrogen, alkalimetal, ammonium, alkanol ammonium, (wherein the alkyl group containsfrom 1 to 4 carbon atoms) or an alkyl group containing from 1 to carbonatoms (it is not necessary that all X groups in the compound beidentical) and R R R R, and R are hydrogen or COOX. At least one of theR R R and R groups must be COOX when R is COOX. Thus, the formula isseen to encompass acid, salt and ester compounds. It is further apparentthat certain of the compounds, for example, those in which R, and R areCOOX and R and R are hydrogen include both cis and trans configurations.

The salt forms of the compounds of thisinvention are useful ascomplexing agents and/or as detergency builders.

Tetrahydrofuran-2,2,3,4,5,S-hexacarboxylate salts, especially in thetrans configurations and preferably the pentasodium salts, are preferredcompounds of the invention in view of their ability to complex more thanone mole of calcium ion per mole of hexacarboxylate salt.

The ester forms of the compounds of this invention compound.

For example: the use of dimethyl maleate will yield a mixture of the cisand trans configurations of whereas the use of dimethyl fumarate willyield the trans form of this compound.

The use of methyl acrylate will yield R'OOC (30011 ROOO \COORH-(l7-(lJCOOCHa The use of methylene malonic ester CH C (COO CH willyield ROOC o COOR 0 c ROOC \COOR TI-$-CCOOCH3 E5 COOCTIJ The use ofethene 1,1,2 trimethylcarboxylate will COOR The use of ethene 1,1,2,2tetramethylcarboxylate W aQO QQH; .QQQQHF.

Higher esters are obtained by use of higher alkyl carboxylate esters inthe reaction or by transesterifying the lower esters with theappropriate alcohol. The R in the COOR groups occupying the 2,2,5,5positions corresponds to the R in the alcohol (ROH) used in the secondreaction.

The reaction shown in the first equation can be conveniently conductedin an inert solvent, e.g., 1,2- dibromoethane, at a temperaturesufficiently high to promote a reasonable rate of reaction, e.g., about120C in the case of dimethyl fumarate. Preferably, the reaction isconducted under reflux and a nitrogen blanket to prevent volatilizationor oxidation of the reactants. The product is recovered by conventionalcrystallization and filtration techniques. Reactions of this generaltype are fully understood by those skilled in the art, and arediscussed, for example, in U.S. Pat. No. 3,317,567.

The alcoholysis reaction shown in the second equation is preferablyconducted by mixing the product of the first reaction with the requisiteamount of water and alcohol cooling to about 0C to 40C; adding gaseousHCl; filtering to remove NH Cl; adding concentrated sulfuric acid as acatalyst and refluxing to complete the reaction.

The corresponding alkali metal salts are readily obtained byconventional saponification techniques (using less than stoichimetricamounts of alkali metal hydroxide if a partial salt such as thepreferred pentasodium tetrahydrofuran 2,2,3,4,5,5-hexacarboxylate isdesired). The corresponding ammonium and alkanol ammonium salts are moreeasily obtained by neutralization of the acid forms of the compounds ofthis invention.

Acidulation of the salt with a strong acid, e.g., HCl, H or a strongacid ion exchange resin, will yield the acid forms of the compounds ofthis invention.

The tetrahydrofuran polycarboxylate salts of this invention are usefulas agents for complexing metal and- /or alkaline earth metal ions inaqueous media. The amount of polycarboxylate required to effectivelycomplex the ions in a given system will depend, to some extent, on theparticular polycarboxylate salt being used and the particular metal andalkaline earth metal ions in the aqueous media. Generally, complexing ismore effective in basic solution. Optimum conditions and amounts ofcomplexing agent can readily be determined by routine experimentation.

The tetrahydrofuran polycarboxylate salts are also useful as builders indetergent formulations. Generally, the use of the alkali metal salts,particularly the sodium salt is preferred. However, in some formulations(such as liquid formulations where greater builder solubility isrequired) the use of ammonium or alkanol ammonium salts may bedesirable.

The detergent formulations of this invention will contain at least 1% byweight and preferably at least 5% by weight of the polycarboxylate saltsof this invention. In order to obtain the maximum advantages of thebuilder compositions of this invention, the use of from 5% to 75% ofthese polycarboxylate salts is particularly preferred. Thetetrahydrofuran polycarboxylic salt compounds of this invention can bethe sole detergency builder or these compounds can be utilized incombination with other detergency builders which may consti tute from 0to 95% by weight of the total builders in the formulation. By way ofexample, builders which can be employed in combination with the novelbuilder compounds of this invention include water soluble inorganicbuilder salts such as alkali metal polyphosphates, i.e., thetripolyphosphates and pyrophosphates, alkali metal carbonates, borates,bicarbonates and silicates and water soluble organic builders includingamino polycarboxylic acids and salts such as alkali metalnitrilotriacetates; cycloalkane polycarboxylic acids and salts, etherpolycarboxylates, alkyl polycarboxylates, epoxy polycarboxylates, othertetrahydrofuran polycarboxylates such as l,2,3,4 or 2,2,5,5tetrahydrofuran tetracarboxylates, benzene polycarboxylates, oxidizedstarches, amino (trimethylene phosphonic acid) and its salts,diphosphonic acids and salts (e.g., methylene diphosphonic acid;l-hydroxy ethylidene diphosphonic acid) and the like.

The detergent formulations of this invention will generally contain from5% to 95% by weight total builder (although greater or lesser quantitiesmay be employed if desired) which, as indicated above, may be solely thetetrahydrofuran polycarboxylic acids and/or salt compounds of thisinvention or mixtures of such compounds with other builders. The totalamount of builder employed will be dependent on the intended use of thedetergent formulation, other ingredients of the formulation, pHconditions and the like. For example, general laundry powderformulations will usually contain 20% to 60% builder; liquid dishwashingformulations 11% to 12% builder; machine dishwashing formulations 60% tobuilder. Optimum levels of builder content as well as optimum mixturesof builders of this invention with other builders for various uses canbe determined by routine tests in accordance with conventional detergentformulation practice.

The detergent formulations of this invention will generally contain awater soluble detergent surfactant although the surfactant ingredientmay be omitted from machine dishwashing formulations. Any water solubleanionic, nonionic, zwitterionic or amphoteric surfactant can beemployed.

Examples of suitable anionic surfactants include soaps such as the saltsof fatty acids containing about 9 to 20 carbon atoms, e.g. salts offatty acids derived from coconut oil and tallow; alkyl benzenesulfonatesparticularly linear alkyl benzene sulfonates in which thealkyl group contains from 10 to 16 carbon atoms; alcohol sulfates;ethoxylated alcohol sulfates; hydroxy alkyl sulfonates; alkyl sulfatesand sulfonates; monoglyceride sulfates; acid condensates of fatty acidchlorides with hydroxy alkyl sulfonates and the like.

Examples of suitable nonionic surfactants include alkylene oxide (e.g.,ethylene oxide) condensates of mono and polyhydroxy alcohols, alkylphenols, fatty acid amides, and fatty amines; amine oxides; sugarderivatives such as sucrose monopalmitate; long chain tertiary phosphineoxides; dialkyl sulfoxides; fatty acid amides, (e.g., mono or diethanolamides of fatty acids containing 10 to 18 carbon atoms), andthe like.

Examples of suitable zwitterionic surfactants include derivatives ofaliphatic quaternary ammonium compounds such as3-(N,N-dimethyl-N-hexadecyl ammonio) propane-l-sulfonate and3-(N,N-dimethyl-N- hexadecylammonio)-2-hydroxy propanel -sulfonate.

Examples of suitable amphoteric surfactants include betains,sulfobetains and fatty acid imidazole carboxylates and sulfonates.

It will be understood that the above examples of surfactants are by nomeans comprehensive and that numerous other surfactants are known tothose skilled in the art. It will be further understood that the choiceand use of surfactants will be in accordance with well understoodpractices of detergent formulation. For example, anionic surfactants,particularly linear alkyl benzene sulfonate are preferred for use ingeneral laundry formulations, whereas low foaming nonionic surfactantsare preferred for use in machine dishwashing formulations.

The quantity of surfactant employed in the detergent formulations ofthis invention will depend on the surfactant chosen and the end use ofthe formulation. In general, the formulations will contain from 5% to50% surfactant by weight, although as much as 95% or more surfactant maybe employed if desired. For example,

general laundry powder formulations normally contain 5% to 50%,preferably to 25% surfactant; machine dishwashing formulations 0.5% to5%; liquid dishwashing formulations 20% to 45%. The weight ratio ofsurfactant to builder will generally be in the range of from 1:12 to2:1.

In addition to builder and surfactant components, detergent formulationsmay contain fillers such as sodium sulfate and minor amounts ofbleaches, dyes, optical brightners, soil anti-redeposition agents,perfumes and the like.

In machine dishwashing compositions the surfactant will be a low-foaminganionic surfactant which will constitute 0 to 5% of the formulation.

The term low-foaming surfactant connotes a surfactant which, in thefoaming test described below, reduces the revolutions of the washerjet-spray arm during the wash and rinse cycles less than 15%, preferablyless than 10%.

In the foaming test, 1.5 grams of surfactant is added to a 1969Kitchen-Aid Home Dishwasher, Model No. KOS-16, manufactured by HobartManufacturing Company which is provided with means for countingrevolutions of the washer jet-spray arm during wash and rinse cycles.The machine is operated using distilled water feed at a machine entrancetemperature of 40C. The number of revolutions of the jet-spray armduring the wash and rinse cycles is counted. The results are comparedwith those obtained by operation of the machine using no surfactantcharge and percentage decrease in number of revolutions is determined.

The surfactant should, of course, be compatible with the chlorinecontaining component hereinafter discussed. Examples of suitablenonionic surfactants include ethoxylated alkyl phenols, ethoxylatedalcohols (both monoand di-hydroxy alcohols), polyoxyalkylene glycols,aliphatic polyethers and the like. The widely commercially utilizedcondensates of polyoxypropylene glycols having molecular weights of fromabout 1400 to 2200 with ethylene oxide (the ethylene oxide constituting5 to 35 weight percent of the condensate) are, for example,advantageously used in the machine dishwashing formulations of thisinvention.

Suitable low-foaming anionic surfactants include alkyldiphenyl ethersulfonates such as sodium dodecyl diphenyl ether disulfonates and alkylnaphthalene sulfonates.

Mixtures of suitable low-foaming surfactants can be utilized if desired.

In addition, machine dishwashing formulations will contain sufficientchlorine providing compound to provide 0.5% to 2% available chlorine.For example, the formulation may contain from 0.5% to 5%, preferably 1%to 3% of a chlorocyanurate or from 10% to 30% chlorinated trisodiumphosphate. Suitable chlorocyanurates are sodium and potassiumdichlorocyanurate; [(monotrichloro) tetra-(mono potassium dichloro)]penta-isocyanurate; (mono-trichloro) (monopotassium dichloro)di-isocyanurate.

Machine dishwashing compositions should additionally contain from 5% to30% soluble sodium silicate having an SiO to Na O mole ratio of from 1:1to 32:1 preferably about 2.4:1 to inhibit corrosion of metal parts ofdishwashing machines and provide over-glaze protection to fine china.

Machine dishwashing compositions will generally contain at least 10%,preferably at least 20% builder, up to a maximum of about builder. Thenew builder compounds of this invention should constitute at least 5% ofthe weight of the machine dishwashing formulation in order to obtain thefull effects of their 7 inherent characteristics.

The invention is further illustrated by the following examples whichdeal with the preparation and use of the particularly preferredtetrahydrofuran 2,2-trans- 3,4,5,5-hexacarboxylate compounds. It will berecognized by those skilled in the art that other compounds of thisinvention can be prepared and utilized in a similar manner pursuant tothe preceding discussion. In the examples, all parts and percentages areby weight unless otherwise indicated.

EXAMPLE I Tetracyanoethylene oxide (56.6 grams); dimethyl fumarate 6.6grams); ethylene dibromide solvent (450 ml.) are maintained at about120C with stirring for trans-3 ,4-dicarboxylate-2,2,5 ,5 ,-tetranitri1eative areas 1:3).

5 positions (relative areas 1:3:4).

EXAMPLE III Pentasodium monohydrogen tetrahydrofuran 2,2-

trans-3,4,5,5 hexacarboxylate (289.2 mg.) is dissolved in 10 ml.deionized water and passed through a column about 22 hours undernitrogen atmosphere in a glass 5 packed with a strong acid ion exchangeresin (sulfoflask fitted with a reflux condenser. A dark brown solunatedpolystyrene marketed by Fisher Scientific Comtion forms which isfiltered while hot to remove minor pany under the trademark Rexyn 101).This procedure amounts of unidentified solid impurities. The filtrate isyields tetrahydrofuran 2,2-trans-3,4,5,5 hexacarboxylic dried on arotary evaporator and the residue washed l0 acid. The titration curve ofthe acid with sodium hywith diethylether and dried under nitrogen. Theresidue droxide exhibits three breaks and indicates that four product ispurified by dissolution in and crystallization protons are highly acidic(apparent pKas equal to or from methyl alcohol followed by vacuumdrying. The less than 5.7); a fifth proton is less acidic (apparentidentity of the Product as dimethyl tetrahydfofuranpKa of about 6.8);and the sixth proton has an apparent is pKa of about 9.1. firmed byelemental analysis and a H nuclear magnetic resonance spectrum indeuterated acetone in which the 3 and 4 protons appear as a singlet at5.45 ppm; the EXAMPLE IV ester CH protons as a singlet at 4.10 ppm vs.TMS (rel- P nt d u n y g tetrahydrofuran p trans-3,4,5,5 hexacarboxylateis tested for sequestra- Ninety grams of the dimethyltetrahydrofuran-trans- On c o ng e Procedures described y3,4-dicarboxylate-2,2,5,S-tetranitrile; 21 grams water; Matzner et al.,Organic Builder Salts as Replacements 1000 ml. methyl alcohol arecharged to a glass flask for Sodium Tripolyphosphate Tenside Detergents,10, and the temperature of the mixture is held between 0 Heft 3, pages 119 through 125 (1973). In this test, the to 40C while 50 grams ofhydrogen chloride gas is bub- 25 divalent ion electrode shows twoseparate end points bled into the mixture. The reaction mixture isfiltered for titration of calcium ion with a solution of the hextoremove ammonium chloride; 1.5 ml. concentrated acarboxylate salt. Thisis due to the formation of 2:1 sulfuric acid is added as catalyst to thefiltrate which is and 1:1 (Ca11/ligand) complexes. The averagesequesthen refluxed for about hours. Upon cooling, solid tration values(intensity multiplied by capacity exproduct separates from the solutionand is removed by 30 pressed as a percentage of sodium tripolyphosphatesefiltration. The solid is dissolved in chloroform; washed questrationvalue are in the range of 138% to 188% dewith 5% sodium bicarbonate andwater. The chloropending upon the complex formed. form solution is driedover magnesium sulfate and the chloroform evaporated to leave an oilyresidue. Disso- EXAMPLE v lution of the residue in methanol followed bycrystallization yields a pure crystalline product. The identity ofDetergent f9rmulatlons Contalnmg the Pement the product as hexamethyltetrahydrofuran 2,2-transbuilder Show" pliable I below; 17% nearalkylben- 3 4 55 hexacarboxylate i fi d b d m zene sulfonate having anaverage molecular weight of analysis and a H nuclear magnetic resonancespectrum about 12% Sodium Silicate; remainder. Sedium u in deuteratedchloroform which exhibits a singlet at fate are p p The formulations arst d by wash- 4.50 ppm corresponding to the 3 and 4 protons; a siningidentically soiled fabric swatches (indicated in the l at 402 ppmcorresponding to th two CH ester table) in water of 200 ppm hardness at40C containing groups at the 3 and 4 positions; a singlet at 3.88 ppm0.15% detergent formulation using identical washing corresponding to thefour ester CH groups at the 2 and techniques. The reflectivity of thesoiled swatches before and after washing is measured instrumentally andthe difference reported in Table I as A Rd. Hi h A Rd EXAMPLE H valuesare indicative of correspondingly hig deter- A mixture of 55.4 gramssodium hydroxide; 100 gency effectiveness.

TABLE I Cotton Fabric ARd Polvester/Cotton Fabric ARd 50% 37.5% 25% 50%37.5% 25% Builder Builder Builder Builder Builder Builder BuilderPentasodium monohydrogen tetrahydrofuran2,2-trans-3,4,5,5-hexacarboxylate 28.7 27.1 21.3 13.5 10.1 9.8 SodiumTripolyphosphate 26.2 19.0 14.5 12.0 8.7 5.7

ml. water; 48.5 grams hexamethyl tetrahydrofuran 2,2- EXAMPLE VI fhexacarboxylate heated f reflux at Three pentasodium monohydrogentetrahydrofuran 90 C for 24 l m glass flask T Solunon2,2-trans-3,4,5,5-hexacarboxylate built detergent for- Cemrated bydlstlllfmon P methanol and water from mulations corresponding to thoseshown in Example V the flask The macho i i cooled l room temexcept thatlinear alkylbenzene sulfonate surfactant is perature and productprecipitated by addition of 1000 replaced with. m1. methanol. Theidentity of the product as pentaso- 6S 1. a nonionic surfactant acondensate of 7 molecudium monohydrogen tetrahydrofuran2,2-trans-3,4,5,5 hexacarboxylate is confirmed by chemical analysis anda H nuclear magnetic resonance spectrum in deuterium oxide exhibiting asinglet at 4.1 ppm.

lar proportions of ethylene oxide with linear secondary alcoholscontaining 11 to 15 carbon atoms 2. an amphoteric surfactant sodiumhydroxyalkyl (alkyl group contains an average of 15 carbon atoms)N-methyltaurate 3. a zwitterionic surfactantcocodimethylsulfopropylbetaine are prepared and tested. All threeformulations exhibit effective detergency.

EXAMPLE VII A machine dishwashing formulation containing 50% pentasodiummonohydrogen tetrahydrofuran 2,2- trans-3,4,5,S-hexacarboxylate; 35% ofan aqueous solution containing 47% sodium silicate having an SiO to Na Omole ratio of 2.4; 3% of a condensate of ethylene oxide withpolyoxypropylene glycol marketed by Wyandotte Chemical Corporation asPluronic L-62; 1.2% potassium dichlorocyanurate; 10.8% sodium sulfate isprepared. The formulation is used to wash soiled dishes and glassware ina conventional automatic home dishwashing machine. Excellent cleaning isobtained and, in particular, the glassware is found substantially freefrom filming and spotting.

EXAMPLE VIII Three machine dishwashing formulations are prepared whichare identical to that of Example VII'except that the followingsurfactants are substituted for the ethylene oxide-polyoxypropyleneglycol:

l. condensate of an internal, vicinal, linear diol having an averagechain length of 16 carbon atoms with 3 molecular proportions of ethyleneoxide 2. condensate of N-decanol with 2- /2 molecular proportionsethylene oxide 3. sodium decydiphenyl ether disulfonate.

All three formulations provide excellent performance in cleaning dishesand glassware in a conventional automatic home dishwashing machine.

Other compounds of this invention can be prepared by techniques similarto those disclosed in Example I.

For example, Table II, below, indicates the esters which are obtained byreaction of various g V r compounds followed by alcoholysis withmethanol.

TABLE II Dimethyl malonate.

Heptamethyl tetrahydrofuran-22,33,4,5,5-heptacarboxylate.

Octamethyltetrahydrofuran- 12E 2, 3,3,4,4,5,5-oetaca.rboxy- Methylacrylate.

'Ietracyano ethylene oxide.

Dimethyl/ methylene malonate.

Trlrnethyl ethene-l,1,2- tricarboxylate.

Tetramethyl ethene-1,1,2,2- tetracarboxylate.

TABLE II Continucd CN 0 CN R1 R3 CN Y R2 R4 Product EthyleneTrimethyl-tetrahydrofuran- 2,2,5-tr1carboxylate. Methyl acrylate.Mixture of els and trans tetra methyl tetrahydrofuran- 2,2,3,5 and2,2,4,5-tetracarboxylates.

Dimethyl Mixture of pentamethyl tetmethylene rahydrolurna-2,2,3,8,5 andmelonate. 2,2,4,4,5-pentaearboxylate.

Dimethyl Mixture of pentamethyl tetfumarate. rahydrofuran-2,2,-trans-3-015-4,5 and 2,2-els-3,5-trans-4 Tricyano ethylene oxide.pentacarboxylate.

Dimethyl Mixture of pentamethyl tetmaleate. rahydrofurna-cis-2,2,3,4,5

and 2,2-cls-3,4-trans-5 pentaearboxylate.

'Irlmethyl Mixture of cis and transhexaethene-1,l,2- methyltetrahydrofurantrlcarboxy- 2,2,3,3,4,5 and 2,2,3,4,4,5 late.hexacarboxylate.

Tetramethyl Heptamethyl tetrahydrofuetheneran-2, 3,3,4,4,5-heptacar-1,1,2,2-tetraboxylate. carboxylate.

Acids corresponding to the esters shown in Table II, above, and theircorresponding totally or partially neutralized salts can be prepared bysaponification and acidulation techniques comparable to thoseexemplified in Examples II and Ill.

What is claimed is:

1. A compound represented by the formula X0 0 o o c 0 02; X00 0 R a s-R2 R3 wherein X is selected from the group consisting of hydrogen,alkali metal, ammonium, alkanol ammonium wherein the alkyl moietycontains from 1 to 4 carbon atoms and alkyl groups containing from 1 to20 carbon atoms; R R R R, and R are selected from the group consistingof hydrogen and COOX, at least one of R R R and R being COOX when R isCOOX.

2. A compound according to claim 1 wherein at least two of R R R and Rare hydrogen.

3. A compound according to claim 1 wherein R is COOX.

4. A compound according to claim 1 wherein X is hydrogen.

5. A compound according according to claim 1 wherein X is alkali metal.

6. A compound according to claim 1 wherein R and R are COOX and R and Rare hydrogen.

7. A compound according to claim 6 characterized by trans orientation ofR and R 8. Pentasodium monohydrogen tetrahydrofuran2,2,3,4,5,5-hexacarboxylate.

9. Pentasodium monohydrogen tetrahydrofuran 2,2-trans-3,4,5,5-hexacarboxylate.

10. l-Iexasodium tetrahydrofuran hexacarboxylate.

l1. Hexasodium tetrahydrofuran 2,2-trans-3,4,5,5- hexacarboxylate.

2. A compound according to claim 1 wherein at least two of R1, R2, R3and R4 are hydrogen.
 3. A compound according to claim 1 wherein R5 isCOOX.
 4. A compound according to claim 1 wherein X is hydrogen.
 5. Acompound according according to claim 1 wherein X is alkali metal.
 6. Acompound according to claim 1 wherein R1 and R4 are COOX and R2 and R3are hydrogen.
 7. A compound according to claim 6 characterized by transorientation of R1 and R4.
 8. Pentasodium monohydrogen tetrahydrofuran2,2,3,4,5,5-hexacarboxylate.
 9. Pentasodium monohydrogen tetrahydrofuran2,2-trans-3,4,5,5-hexacarboxylate.
 10. Hexasodium tetrahydrofuran2,2,3,4,5,5-hexacarboxylate.
 11. Hexasodium tetrahydrofuran2,2-trans-3,4,5,5-hexacarboxylate.